Toward a unified theory of sexual mixing and pair formation.

Sexually transmitted diseases such as gonorrhea, syphilis, herpes, and AIDS are driven and maintained in populations by epidemiological and sociological factors that are not completely understood. One such factor is the way in which people mix sexually. In this paper, we outline a unified approach to modeling sexual mixing structures, where such structures are defined in terms of a set of axioms for a finite number of distinct groups of people. Theorems for homosexual, heterosexual, and arbitrary group mixing are presented, leading to a representation of all mixing structures defined by the axioms. The representation and its parameters are interpreted in terms of intergroup affinities for sexual mixing. The use of the approach in sexually transmitted disease modeling is discussed.     

Cluster analysis of behavioural and event-related potentials during a contingent negative variation paradigm in remitting-relapsing and benign forms of multiple sclerosis

Background  

Event-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile.     

Biological characterization of the lytic cycle of actinophage φA7 in Streptomyces antibioticus

Some basic parameters of the lytic development of phage phi A7 in Streptomyces antibioticus are described. One-step growth experiments demonstrated that at 28 degrees C phi A7 has a latent period of about 60 min and an exponential growth period of about 35 min. The average burst size ranged from 70-100 plaque forming units per infected cell. At the same temperature 50% of the virions were adsorbed to germ tubes of S. antibioticus in about 10 min. This corresponds to an adsorption constant of 6.5 x 10(-10) ml/min. The phage was unable to adsorb the host at other stages of the life cycle (spores or mycelium). Divalent cations are not required for phi A7 stability but Ca2+ proved to be essential for adsorption and also for a later stage of the vegetative development of the phage.     

Glucosinolate contents in maca (Lepidium peruvianum Chacón) seeds, sprouts, mature plants and several derived commercial products

Several products derived from processed maca hypocotyls (Lepidium peruvianum Chacón, previously known asL. meyenii Walp.) were surveyed for glucosinolate content and quantified by HPLC analysis. These included pills, capsules, flour, liquor, tonic and mayonnaise. Different plant organs such as fresh hypocotyls and leaves, seeds, dry hypocotyls, and sprouts were also included in the survey. The most abundant glucosinolates detected in fresh and dry hypocotyls and leaves were the aromatic glucosinolates, benzylglucosinolate (glucotropaeolin) and p-methoxybenzylglucosinolate. Maca seeds and sprouts differed in profile from hypocotyls and leaves due to the modification of benzylglucosinolate. No glucosinolates were detected in liquor and tonic, while mayonnaise had only trace amounts of those glucosinolates. It had instead allylglucosinolate (sinigrin), which is an aliphatic glucosinolate. The pills, capsules and flour had the same glucosinolates as those observed in hypocotyls, but in variable amounts. The richest sources of glucosinolates were seeds, fresh hypocotyls and sprouts, in that order.     

TBCD Links Centriologenesis,Spindle Microtubule Dynamics,and Midbody Abscission in Human Cells

Microtubule-organizing centers recruit α- and β-tubulin polypeptides for microtubule nucleation. Tubulin synthesis is complex, requiring five specific cofactors, designated tubulin cofactors (TBCs) A–E, which contribute to various aspects of microtubule dynamics in vivo. Here, we show that tubulin cofactor D (TBCD) is concentrated at the centrosome and midbody, where it participates in centriologenesis, spindle organization, and cell abscission. TBCD exhibits a cell-cycle-specific pattern, localizing on the daughter centriole at G1 and on procentrioles by S, and disappearing from older centrioles at telophase as the protein is recruited to the midbody. Our data show that TBCD overexpression results in microtubule release from the centrosome and G1 arrest, whereas its depletion produces mitotic aberrations and incomplete microtubule retraction at the midbody during cytokinesis. TBCD is recruited to the centriole replication site at the onset of the centrosome duplication cycle. A role in centriologenesis is further supported in differentiating ciliated cells, where TBCD is organized into “centriolar rosettes”. These data suggest that TBCD participates in both canonical and de novo centriolar assembly pathways.     

Other developments regarding the concept of energy in biological systems

In order to recognize the realizability of inputs with different physical natures through a component, Yoneda's Lemma is applied. The major utility of this Lemma is when the components produce only energy. From this, it is assumed that a new material input must exist which was not recognized in the original developments in biological systems representation. Moreover, simple transfers of energy, between objects, components, and among both objects and components are developed under the generic name; energetical evolution. Thus, energetical evolution appears as anew element in the abstract representation of biological systems. These new concepts are incorporated into a new abstract diagram and a newM _β category. This paper was made possible by a Fellowship from the Consejo Nacional de Investigaciones Científicas y Técnicas of the República Argentina.     

Vicariance patterns in the Mediterranean Sea: east–west cleavage and low dispersal in the endemic seagrass Posidonia oceanica

Aim The seagrass, Posidonia oceanica is a clonal angiosperm endemic to the Mediterranean Sea. Previous studies have suggested that clonal growth is far greater than sexual recruitment and thus leads to low clonal diversity within meadows. However, recently developed microsatellite markers indicate that there are many different genotypes, and therefore many distinct clones present. The low resolution of markers used in the past limited our ability to estimate clonality and assess the individual level. New high‐resolution dinucleotide microsatellites now allow genetically distinct individuals to be identified, enabling more reliable estimation of population genetic parameters across the Mediterranean Basin. We investigated the biogeography and dispersal of P. oceanica at various spatial scales in order to assess the influence of different evolutionary factors shaping the distribution of genetic diversity in this species. Location The Mediterranean. Methods We used seven hypervariable microsatellite markers, in addition to the five previously existing markers, to describe the spatial distribution of genetic variability in 34 meadows spread throughout the Mediterranean, on the basis of an average of 35.6 (± 6.3) ramets sampled. Results At the scale of the Mediterranean Sea as a whole, a strong east–west cleavage was detected (amova) . These results are in line with those obtained using previous markers. The new results showed the presence of a putative secondary contact zone at the Siculo‐Tunisian Strait, which exhibited high allelic richness and shared alleles absent from the eastern and western basins. F statistics (pairwise θ ranges between 0.09 and 0.71) revealed high genetic structure between meadows, both at a small scale (about 2 to 200 km) and at a medium scale within the eastern and western basins, independent of geographical distance. At the intrameadow scale, significant spatial autocorrelation in six out of 15 locations revealed that dispersal can be restricted to the scale of a few metres. Main conclusions A stochastic pattern of effective migration due to low population size, turnover and seed survival is the most likely explanation for this pattern of highly restricted gene flow, despite the importance of an a priori seed dispersal potential. The east–west cleavage probably represents the outline of vicariance caused by the last Pleistocene ice age and maintained to this day by low gene flow. These results emphasize the diversity of evolutionary processes shaping the genetic structure at different spatial scales.     

Taste systems of the petrosal ganglion of the rat glossopharyngeal nerve

Single unit recordings were taken from sensory ganglion cellsin the petrosal ganglion (PG) of the glossopharyngeal nerveof the rat. These taste units were examined with respect tospontaneous and evoked discharge patterns and responsivenessto a wide variety of chemical compounds, most of natural occurrence.Spontaneous activity patterns, with few exceptions, tended tobe extremely irregular with both bursting (clusters of 2–3spikes) and grouping (large groups of spikes as in evoked discharges).Most interspike interval histograms of spontaneous activitywere multimodal, similar to rat geniculate ganglion (GG) units.Evoked discharges usually displayed grouping of spikes, andlong latencies of onset and persistence of discharge after rinsewere sometimes seen. Little response was shown to nucleotidesor salts. Units responsive to amino acids tended to show largedischarge to only one or two amino acids; and the most responsiveamino acid usually varied from cell to cell. Units responsiveto alkaloids only responded to a few alkaloids with atropineand quinine being the most stimulatory. Units responsive toacids only discharged to a few of the acids tested and oftenacids of low pH elicited no discharge. Saccharin activated unitsresponsive to both sugar and alkaloids. A few units highly responsiveto both sugar and alkaloids were seen. The units were placedinto four clusters on the basis of chemicals activating themand certain neurophysiological characteristics: PG salt units,PG acid units and, tentatively, amino acid (sugar) units andX (alkaloid and alkaloid plus) units. The PG salt units didnot show the exclusive sensitivity to sodium and lithium compoundsas did the GG salt units. The PG acid units could also be differentiatedfrom the GG acid units. The petrosal amino acid and X units,on the other hand, could not be differentiated from similarunits in the rat GG.     

Canine lymphoma-associated antigens defined by murine monoclonal antibodies

Summary Lymphoma in dogs resembles human non-Hodgkin's lymphoma in pathological presentation, immunophenotype, and response to therapy, thus representing a good model for comparative studies with human disease. Monoclonal antibodies (MAbs) were derived from mice immunized with a dog lymphoma cell line. Three MAbs were selected for further application in immunophenotyping and immunotherapy. The binding specificities, antigen characterization, and isotypes for these MAbs are described.Supported by NCI grant CA-10815